Internet Protocol Television or IPTV is a term used to refer to the delivery of television and video (collectively referred to below as “TV”) over IP-based communication networks. IPTV is in fact a collection of protocols including compression, playout, and distribution protocols. In terms of distribution across networks, three classes have been defined, namely multicast, unicast, and peer-to-peer distribution.
Of these, it is envisaged that multicast will be used mainly for live-streaming of TV. Multicast relies upon the IETF defined Internet Group Management Protocol (IGMP) to create and change multicast receiver groups at multicast agents within an IP network. Multicast agents receive TV and multicast it onwards to group members. Multicast is a very effective mechanism for transporting a set of TV channels to a large number of viewers.
Multicast is not however a suitable distribution mechanism for so-called “time-lapse TV”, where a viewer can pause a live-TV program and then resume watching it at a later time, or “timeshift TV” where previously aired TV programmes can be viewed at a later time. IPTV, like satellite TV or cable TV, usually only allows the watching of time-shifted content if the user had configured the system in advance to record that specific content, through the use of personal video recorders (PVRs). It is also possible to have network-based PVRs, allowing users to receive time-shifted content from the network via unicast, but in this case, there are significant cost implications due to the infrastructure required to handle all these unicast streams. Unicast distribution typically relies upon the Real Time Streaming Protocol (RTSP) which allows a client to remotely control a streaming media server. Unicast creates individual sessions for each connected user, so the same content will get transferred once per user over the network and therefore can be used as a method for delivery of Video-on-Demand, time-lapse TV and similar (more personal) TV services. However, a disadvantage of unicast distribution is that it consumes a large amount of bandwidth in the network and resources in the media server making this type of delivery not cost effective.
Peer-to-peer distribution (also know as “P2P”) uses each client and/or node in a network for the distribution of media. When a program is viewed by a given client/node, different parts of the program can be downloaded from different neighbouring clients/nodes. Network operators might want to implement restricted P2P distribution within their own networks, with content being cached at multiple nodes within a given network for onward transfer to clients. Clients may or may not be able to share content between each other. P2P has a lot of advantages and lies somewhere in between unicast and multicast when it comes to bandwidth usage.
However, problems arise in the implementation of a P2P IPTV system because the media content must be ingested. The original streamed multicast TV signals must be cached, usually at multiple network nodes, and then shared in an ordered manner among the caching nodes. The present invention relates to a method, and system architecture for implementing the method, of ingesting multicasted media content into a peer-to-peer network.